FRQ Mock Test — 4문항 90분 실전

The WordList class contains a list of words and provides operations on those words. Part of the class is shown below.

public class WordList {
    /** A list of words. */
    private ArrayList<String> words;

    // constructor and other methods not shown

    /** Returns the number of words in the list that have at least minLen letters. */
    public int countLongWords(int minLen) { /* to be implemented in part (a) */ }

    /** Returns a new String formed by joining the first letter of each word, in order. */
    public String firstLetters() { /* to be implemented in part (b) */ }
}

Part (a) (4 points): Write the method countLongWords. The method returns the number of words in words with length greater than or equal to minLen. Use a loop and the String length() method.

Part (b) (3 points): Write the method firstLetters. The method returns a single String formed by concatenating the first character of each word in words, in order. Use the String substring or charAt method. Assume every word has at least 1 character.

The StudyTimer class represents a simple study timer that tracks how many minutes a student has studied. Write the complete class based on the following specifications.

Constructor: StudyTimer(String studentName) — creates a new timer for the named student with 0 initial minutes.

Methods:

• public void addSession(int minutes) — adds the given minutes to the total. Assume minutes is positive.
• public int getTotalMinutes() — returns the total minutes studied.
• public String getReport() — returns a string in the form "name: X min" where X is the total. Example: a timer for "Jeongyeon" with total 45 returns "Jeongyeon: 45 min".

Use private instance variables. The class must include a class header, instance variables, constructor, and three methods.

The QuizScores class stores quiz scores in an ArrayList<Integer>. The class includes the method removeBelow(int passingScore), which removes all scores from the list that are strictly less than passingScore and returns the number of scores removed.

public class QuizScores {
    private ArrayList<Integer> scores;

    /** Returns the number of scores removed. */
    public int removeBelow(int passingScore) { /* to be implemented */ }
}

Example: if scores initially contains [78, 45, 92, 60, 33, 88] and passingScore is 60, after the call scores should contain [78, 92, 60, 88] and the method should return 2.

Implement removeBelow. Avoid ConcurrentModificationException by either iterating in reverse with an index-based loop, or by collecting indices to remove first.

The Grid class stores integers in a 2D array int[][] grid. Write the method rowSums that returns a new 1D int array where the i-th element is the sum of row i of grid.

public class Grid {
    private int[][] grid;

    /** Returns a new int array where element i is the sum of row i. */
    public int[] rowSums() { /* to be implemented */ }
}

Example: if grid is

{ {1, 2, 3},
  {4, 5, 6},
  {7, 8, 9} }

then rowSums() returns {6, 15, 24}.

Assume the grid has at least 1 row and all rows have the same length.